A particular field in which often an object of interest like a catheter needs to be localized in a subject like a human body is electrophysiology (EP). Thus, there is a particular relation between the present invention and cardiac electrophysiology (EP) and more specifically X-Ray-guided ablation and pacemaker placement procedures.
In order to automatically locate EP catheters in 3D (e.g. for electro-anatomical or ablation mapping), it may be necessary to track them in two-dimensional X-Ray images and extrapolate the 3D position from the 2D information. Examples of such an approach include: doing the tracking in two simultaneous images provided by a stereo or bi-plane X-Ray system as in U.S. Pat. No. 7,050,844, so that a 3D position may be deduced from the two view angles.
However, tracking of an EP catheter in 2D X-Ray images is difficult in the general case for several reasons, including the following:
In order to allow real-time imaging without exposing the patient to an excessive amount of radiations, the X-Ray dose in fluoroscopic images is generally low and, thus, the image quality is poor.
Many objects which are visible in a fluoroscopic image might be mistaken for EP catheters (e.g. ECG leads and patches, stitches, injection catheters, etc.).
A number of EP catheters may be used at the same time (e.g. for mapping catheters of various shapes, ablation catheter and reference catheters) but not all of them need to be tracked, while they may interfere in the tracking of those of particular interest.
Thus, as usually during EP procedures, many catheters of various types and shapes are used (e.g. reference, mapping or ablation), additional object are present which may be confused with catheters and the image quality of fluoroscopic images provided is rather poor, classical detection and tracking methods are likely fail in capturing the object(s) of interest correctly.